Vietnam Airlines apologized to a group of three passengers, on Wednesday, for an overbooking error which bumped them off a June 6 flight out of Dong Hoi Airport in Quang Binh Province.

The national carrier said though the error was "unexpected," it would try its best never to repeat it.

The 13-member family arrived at Dong Hoi Airport with round-trip tickets to Hanoi. Their flight was scheduled to depart at 8.20 p.m.

However, they were informed that only 10 of them could have seats.

Vietnam Airlines representatives offered the family a conneting flight to Hanoi, through Ho Chi Minh City and promised to pay compensation to the three stranded passengers -- including money and vouchers for food and drink, according to regulations.

The family members said they were still waiting for an explanation from the airline when the plane took off. In the end, they opted to take a train to Hanoi.

According to Vietnam Airlines, however, the other ten members agreed to board the plane and had their luggage checked in. For some reason, the airline maintains, the group didn't enter the departure lounge although Vietnam Airlines said they had repeatedly asked the passengers to board the plane.

The airline said that the flight was delayed for nearly 25 minutes while ground crew removed their luggage from the plane.